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Biomedical subjects

I Roberts

Publications and source records attributed to I Roberts.

At least 163 records · Page 9Linked to original sources
PubMed1997

Late onset haemolysis and red cell autoimmunisation after allogeneic bone marrow transplant.

We reviewed the medical records of 293 patients who underwent allogeneic bone marrow transplants at the Hammersmith Hospital between 1989 and 1994. There was clinical evidence of an autoimmune reaction against red cells in nine patients. Seven of these patients had significant haemolysis; the other two had red cell autoagglutination. Haemolysis was resistant to treatment in three cases. Six of the nine patients had monoclonal Ig bands identified within 1 year of transplant. The autoimmune reaction could be classified broadly into two types: an early onset type (n = 4) beginning 2 to 8 months post-transplant associated with a cold antibody, and a late onset type (n = 5) beginning 6 to 18 months post-transplant associated with warm antibodies. The predominant antibody in the two categories described may reflect the kinetics of immune reconstitution post-transplant, since serum IgM levels typically return to normal 2 to 6 months post-transplant, while IgG levels may not reach normal levels until 12-18 months post-transplant. We speculate that unbalanced reconstitution of B and T cell lymphopoiesis post-transplant may favour emergence of oligoclonal proliferation and that some of the resulting antibodies may have activity against red cells.

ABO Blood-Group System↗
PubMed1997

Successful second bone marrow transplant for Fanconi's anaemia following escalation of conditioning.

Allogeneic bone marrow transplantation represents the treatment of choice for severe bone marrow failure in patients with Fanconi's anaemia (FA). In view of the increased sensitivity to alkylating agents documented in this condition, much attention has focused on reducing the conditioning chemotherapy. We present a 13-year-old girl in whom sibling allogeneic BMT after conditioning with low-dose cyclophosphamide only resulted in graft rejection. However, a second transplant using the same donor proved successful following a more intensive conditioning regimen. This case demonstrates the phenotypic variability of FA, and highlights the need for tailoring the conditioning regimen for a given patient.

Adolescent↗
PubMed1997

Walking to school and traffic exposure in Australian children.

Daily patterns of pedestrian activity in young children have important health implications, primarily because of the risk of road traffic injury, but also because they may reflect the commencement of exercise habits with long-term consequences. A cross-sectional survey in two Australian cities, Melbourne and Perth, aimed to collect, by parent self-administered questionnaire, population-based data on modes of travel, numbers of street crossings (both accompanied and unaccompanied by an adult), and sociodemographic factors for six- and nine-year-old children. Results indicate that 35 per cent (95 per cent confidence interval (CI) 31 to 39 per cent) and 31 per cent (CI 28 to 34 per cent) walk to school in Melbourne and Perth respectively, while over 60 per cent are driven to school by car, with very small proportions riding bicycles or taking public transport. A higher level of walking was associated with lower levels of several indicators of socioeconomic status. Logistic regression analysis showed that the strongest predictor of walking activity was school type (government versus independent), and after adjusting for this, lesser car ownership, non-English-speaking background and lower occupational category were associated with walking to school, while a different set of predictors--age, sex and maternal education--was associated with the unaccompanied crossing of streets. There was little difference in overall walking levels between boys and girls, but boys were significantly more likely to cross streets unaccompanied (adjusted odds ratio 1.41, CI 1.14 to 1.72), providing a partial explanation of documented sex differences in injury rates.

Accidents, Traffic↗
PubMed1997

An international study of the exposure of children to traffic.

OBJECTIVES: To examine the extent of international differences in children's exposure to traffic as pedestrians or bicyclists. DESIGN: Children's travel patterns were surveyed using a parent-child administered questionnaire. Children were sampled via primary schools, using a probability cluster sampling design. SETTING: Six cities in five countries: Melbourne and Perth (Australia), Montreal (Canada), Auckland (New Zealand), Umeå (Sweden), and Baltimore (USA). SUBJECTS: Children aged 6 and 9 years. MAIN OUTCOME MEASURES: Modes of travel on the school-home journey, total daily time spent walking, and the average daily number of roads crossed. MAIN FINDINGS: Responses were obtained from the parents of 13423 children. There are distinct patterns of children's travel in the six cities studied. Children's travel in the three Australasian cities, Melbourne, Perth and Auckland, is characterised by high car use, low levels of bicycling, and a steep decline in walking with increasing car ownership. In these cities, over a third of the children sampled spent less than five minutes walking per day. In Montreal, walking and public transport were the most common modes of travel. In Umeå, walking and bicycling predominated, with very low use of motorised transport. In comparison with children in the Australasian and North American cities, children in Umeå spend more time walking, with 87% of children walking for more than five minutes per day. CONCLUSIONS: There are large international differences in the extent to which children walk and cycle. These findings would suggest that differences in 'exposure to risk' may be an important contributor to international differences in pedestrian injury rates. There are also substantial differences in pedestrian exposure to risk by levels of car ownership-differences that may explain socioeconomic differentials in pedestrian injury rates.

Australia↗
PubMed1996

Reducing accident death rates in children and young adults: the contribution of hospital care. Steering Committee of the Major Trauma Outcome Study Group.

OBJECTIVE: To assess the contribution of trauma care to the recent decline in accident death rates among children and young people. DESIGN: Logistic regression modelling of temporal trends in the probability of death in patients admitted to hospital for the treatment of severe injury. SETTING: Hospitals participating the United Kingdom major trauma outcome study. SUBJECTS: 3230 patients with an injury severity score of 16 or more, who were admitted for more than three days, transferred or admitted to intensive care, or died from their injuries. MAIN OUTCOME MEASURES: Death or survival in hospital within three months of injury. RESULTS: Over the seven year period 1989-95 there was a substantial decline in the probability of death among children and young adults admitted to hospital after severe injury. The overall estimate of the reduction in the odds of death was 16% per year (odds ratio for the yearly trend 0.84; 95% confidence interval 0.79 to 0.89). This decline did not differ significantly between age groups. (0-4 years 0.79; 5-14 years 0.87; 15-24 years 0.83). CONCLUSIONS: Reductions in hospital case fatality have made an important contribution to reaching the Health of the Nation targets. The contribution of hospital care in the reduction of accident mortality should be taken into account in decisions about the allocation of resources to preventive and curative services.

Accidents↗
PubMed1996

Nitric oxide regulates cell proliferation during Drosophila development.

Cell division and subsequent programmed cell death in imaginal discs of Drosophila larvae determine the final size of organs and structures of the adult fly. We show here that nitric oxide (NO) is involved in controlling the size of body structures during Drosophila development. We have found that NO synthase (NOS) is expressed at high levels in developing imaginal discs. Inhibition of NOS in larvae causes hypertrophy of organs and their segments in adult flies, whereas ectopic expression of NOS in larvae has the opposite effect. Blocking apoptosis in eye imaginal discs unmasks surplus cell proliferation and results in an increase in the number of ommatidia and component cells of individual ommatidia. These results argue that NO acts as an antiproliferative agent during Drosophila development, controlling the balance between cell proliferation and cell differentiation.

Animals↗
PubMed1996

Does the decline in child injury mortality vary by social class? A comparison of class specific mortality in 1981 and 1991.

OBJECTIVE: To examine whether the decline in child injury death rates between 1981 and 1991 varied by social class. DESIGN: Comparison of class specific child injury death rates for 1979, 1980, 1982, and 1983, with those for the four years 1989-92. SETTING: England and Wales. SUBJECTS: Children aged 0-15 years. MAIN OUTCOME MEASURES: Death rates from injury and poisoning. RESULTS: Death rates from injury and poisoning have fallen for children in all social classes. The decline for children in social classes IV and V (21% and 2% respectively), however, is smaller than that for children in social classes I and II (32% and 37%). As a result of the differential decline in injury death rates, socioeconomic mortality differentials have increased. In the four years 1979-80 and 1982-83 the injury death rate for children in social class V was 3.5 times that of children in social class I. For the four years 1989-92 the injury death rate for children in social class V was 5.0 times that of children in social class I. Poisson regression modelling showed that the trend in the decline in death rates across the social classes was unlikely to have arisen by chance alone. CONCLUSIONS: Socioeconomic inequalities in child injury death rates have increased. If these gradients persist, the Health of the Nation's target is likely to be met for children in the non-manual social classes but not for those in the manual social classes.

Adolescent↗
PubMed1996

Clinical, immunological, and pathological consequences of Fas-deficient conditions.

BACKGROUND: The surface molecule named Fas/CD95, which is expressed on activated lymphocytes, can trigger cell death following interaction with its ligand (Fas L). This Fas-Fas-L interaction is thought to be a major regulatory mechanism for controlling the life span of peripheral lymphocytes, and therefore autoimmunity. METHODS: We assessed clinical, immunological and pathological features in three children who inherited mutations of the Fas-encoding gene. One infant had a genomic homozygous deletion, while two siblings had a heterozygous mutation in the fas gene. FINDINGS: The patient with a complete lack of Fas protein expression had prenatal onset of massive lymphoproliferation, which involved the spleen, the liver, and the intrathoracic and abdominal lymph nodes. Lymphoproliferation mainly involved T cells negative for the CD4 and CD8 receptors. These cells, which had a high mitotic index, were essentially found in the T cell zones of lymphoid organs. Active cell division was indicated by a rapid rise in the lymphocyte count following a chemotherapy-induced reduction in the lymphocyte burden. Despite the total Fas protein deficiency, limited autoimmunity was found in this child at age 1 year. A lymphoproliferative syndrome with similar characteristics--but less intense than in the patient with complete Fas deficiency--also occurred from a young age in the siblings with a fas gene mutation on one allele only. One sibling developed neutropoenia, autoimmune haemolytic anaemia, and severe recurrent thrombocytopoenia. INTERPRETATION: Fas-deficiency causes a non-malignant syndrome characterised by the accumulation of dividing lymphocytes. Severity of disease is probably related to the degree of functional Fas deficiency. Heterozygous fas gene mutations, like homozygous deletions, can also be expressed in various cells and tissues and may predispose towards autoimmune disorders. Fas deficiency should be considered in children with enlarged peripheral lymphoid organs and hyperimmunoglobulinaemia, and sometimes the occurrence of autoimmune manifestations towards blood cells.

Anemia, Hemolytic↗
PubMed1996

Safely to school?

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Adolescent↗